engleski

How, how much, and when are U_A (1) and chiral symmetry restored: η' , η and axions

We express the QCD topological susceptibility χ(T) through quark condensates calculated in two effective Dyson-Schwinger models of nonperturbative QCD. They exhibit the correct chiral behavior, including the dynamical breaking of chiral symmetry and its restoration at high temperature T. This is reflected in the U_A(1) symmetry breaking and restoration through χ(T), which yields the T-dependence of the U_A(1)-anomaly-influenced masses of η' and η mesons consistent with experiment. This in turn supports our prediction for the T- dependence of the axion mass. Another support is a rather good agreement with the pertinent lattice results. This agreement is not spoiled by our varying u and d quark mass parameters out of the isospin limit.

QCD topological susceptibility ; temperature dependence ; axion ; η' and η meson masses ; axial anomaly ; chiral symmetry restoration

Mrežna stranica znanstvenog skupa The 40th Max Born Symposium: https://events.ift.uni.wroc.pl/event/61/